Sending current through the earth is certainly more than 500 miles. As for his other inventions, there are certainly some that may have never made it to mainstream usage. His Alternating Current was almost squashed by Edison. Quite a few of his other inventions never made it out either, as most of his notes were destroyed in a fire before he died.

Well hello again! Of course there is a 'short cut' through the earth. But even if what you are talking about is real there is two problems that I see. 1 The short cuts through the earth are only good at long range (Over a 1000 miles).

2 There is no way that a secret like this can be kept.

2A Would not something like this be cool?

Hi!!

It would be very cool if something like that were indeed possible. Maybe a bit scary in the wrong hands. I dont think it was really a secret in the first place. A publicity stunt gone wrong perhaps, but people knew about it before hand. Also, there are things that Tesla did and discovered that are still being examined by scientists. I have no doubt that some of the ideas that Tesla came up with would escape even modern intellect. How long would it have taken us to discover some of the breakthroughs that he discovered nearly a century ago? Surely there are some things that we haven't yet discovered that were lost with his death.

Who knows if his Wardenclyffe experiments actually caused the tunguska incident. Regardless, I would say that harnessing the earth as a giant capacitor could possibly have some strange effects. As far as the short cuts through the earth, Im not sure how relevant that is since new york (where the facility is) is more or less on the opposite side of the earth as Tunguska.

Nevertheless, I don't know enough about any of it to make an educated guess about what could have happened. Just that it is some interesting food for thought.